Nielsen will play 'Ramona', "a smart, beautiful attorney with far-reaching Cook County connections".

Also new this season are theatre vets Steven Pasquale and Taye Diggs.

THE GOOD WIFE's sixth season premieres on September 21 on CBS.

Nielsen's upcoming big screen projects include All Relative, The Runner and Terra Infirma. She last starred in the dark TV drama The Following and was recently seen in the films Return to Zero, 3 Days to Kill and Nymphomaniac. Among her other TV credits are Boss and Law & Order: SVU.

About THE GOOD WIFE: THE GOOD WIFE is a drama starring Emmy Award winner Julianna Margulies as a wife and mother who boldly assumes full responsibility for her family and re-enters the workforce after her husband's very public sex and political corruption scandal lands him in jail. Pushing aside the betrayal and crushing public humiliation caused by her husband, Peter, Alicia Florrick starts over by pursuing her original career as a defense attorney. As a junior associate at a prestigious Chicago law firm, she joins her longtime friend, former law school classmate and firm partner Will Gardner, who is interested in rekindling their former relationship. The firm's top litigator and other partner, Diane Lockhart, likes Alicia's work and her connections so she and Will award her with a full-time associate position following a trial period. Alicia beat out Cary Agos, a clever young attorney who takes a job in the state's attorney's office, now bitter and vengeful. Alicia finds an ally and a friend in Kalinda, the firm's tough and mysterious in-house investigator. Gaining confidence every day, Alicia transforms herself from embarrassed politician's scorned wife to resilient career woman, especially for the sake of providing a stable home for her children, 14-year-old Zach and 13-year-old Grace. Now that Peter is back home and planning to run for office again with help from Eli Gold, his cunning image consultant, Alicia continues to redefine herself and her role in her family's life.